In mathematics, entities are known that have undecidable or non-Turing-computable properties. So, these entities have more properties (there are more true statements about them) than can be derived in any specific formal theory. The theories can always be extended to cover more cases, but the extended theories are incomplete again. Such mathematical entities are #proteons.
If proteons occur in mathematics, there is no a-priori reason why physical reality shouldn't be #protean too. #philosophy

An entity (in mathematics or physical reality) for which all descriptions in terms of formal theories or algorithms are incomplete I call a #proteon. The corresponding adjective is #protean. An entity for which a description by means of a formal theory or algorithm exists, on the other hand, is a (formalizable) system. It is systematic.
(The term "proteon" was coined after the minor greek god Proteus who, according to the Odyssey, could change his shape.) #philosophy